This invention relates to a method of bending a glass plate through heating, particularly, with a small radius of curvature of the bend.
As a typical example of known methods of bending a glass plate with a relatively small radius of curvature of the bend, Japanese Patent Application, Publication No. 45(1970)-28911 proposes to groove a glass plate on an intended bending line and, after heating of the glass plate to soften it in a zone containing the groove, accomplish bending along the groove. From the viewpoint of productivity in industrial applications the need of a machining process for the grooving as a preparatory step is a disadvantage hard to disregard.
Another example is a method disclosed in Japanese Patent Application Ser. No. 47(1972)-39524 now laid open to the public as Disclosure No. 47(1972)-39117. In this method, an electrically conductive paste (containing a metal powder) is applied to the surface of a glass plate so as to provide a conductive layer in the shape of a belt or lane on an intended bending line, and an electric current is made to flow through the conductive layer thereby to heat and soften the glass plate in an area covered with this layer. This method too needs a preparatory process, i.e. the application of the paste. Besides, this method involves a problem that the paste remains fixed to the glass article obtained by bending as an opaque and stained zone, which of course injures the appearance of the article.